1. Field of the Invention
This invention relates to liquid microbiocidal solutions containing a solvent having an alkanol moiety, a microbiocidal compound dissolved in the solvent and a phenolic antioxidant.
This invention also relates to compositions comprising a carrier, a microbiocidal compound, a consolvent for the microbiocidal compound having an alkanol moiety which is also compatible with the carrier (solvent) and a phenolic antioxidant.
The present invention further relates to a process for imparting microbiocidal properties to polymer compositions comprising adding to the polymer composition a liquid microbiocidal solution comprising a cosolvent having an alkanol moiety, a microbiocidal compound dissolved in the cosolvent and a phenolic antioxidant.
This invention further relates to compositions comprising a solution of a liquid plasticizer for vinyl resins, a biologically effective amount of a microbiocidal compound, a cosolvent having an alkanol moiety for the microbiocidal compound and liquid plasticizer, and a phenolic antioxidant.
This invention further relates to vinyl resin compositions comprising an admixture of a vinyl resin and a vinyl resin plasticizer containing, in an amount sufficient to impart microbiocidal properties to the vinyl resin composition, a microbiocidal compound dissolved in a cosolvent having an alkanol moiety and a phenolic antioxidant.
2. Prior Art
It is presently common practice to protect polymer or plastic compositions from microbiocidal, e.g., bacterial or fungal, attack by incorporating microbiocidal compounds into the polymer or plastic compositions. The resulting polymer compositions prevent the deterioration of articles formed from the polymer compositions which is due to microbiological attack on the plasticizers or other polymer additives which are normally incorporated into the polymer compositions to impart desirable physical properties to the articles and to facilitate forming of the articles.
Many of the available microbiocidal materials are solid, and in order to incorporate them homogeneously into polymer compositions, it is necessary to first mix them with liquids which solubilize or disperse the microbiocidal materials uniformly and, thereafter, mix the thus-formed liquid compositions with the polymers. Unfortunately, the solubilities of many of the microbiologically active compounds in the more common solvents are quite low. Therefore, it is either difficult to incorporate a sufficiently high concentration of a microbiocidal compound with a polymer or, if a sufficiently high concentration of the microbiocidal compound can be incorporated in the polymer, an undesirably high concentration of the solvent must also be incorporated into the polymer, compromising the desirable characteristics of the polymer composition.
Attempts to solve these problems have met with varying, often limited, success. For example, U.S. Pat. No. 3,288,674 issued Nov. 29, 1966 to Yeager and U.S. Pat. No. 3,689,449 issued Sept. 5, 1972 to Yeager and Wilson disclose the use of solvents having a labile hydrogen, preferably nonyl phenol, to dissolve microbiocidally active phenoxarsine compounds, the resulting solutions being subsequently incorporated into polymeric resin compositions. Unfortunately, the solubilities of phenoxarsines in nonyl phenol are limited to low concentrations which necessitates incorporating nonyl phenol in the resin at higher concentrations than desirable in order to attain the desired phenoxarsine levels in the polymeric resins.
U.S. Pat. No. 3,360,431 issued December 1967 to Yeager discloses the use of labile hydrogen-containing solvents, preferably nonyl phenol, to dissolve microbiocidally active arsenobenzene compounds for subsequent addition to polymeric resin compositions.
U.S. Pat. No. 4,624,679 describes the advantageous use of aryl alkanols, such as benzyl alcohol, as cosolvents for microbiocidal agents which are to be formulated into solutions with carriers, such as plasticizers and/or other processing aids. The application teaches that aryl alkanol cosolvents, such as benzyl alcohol, increase the levels of microbiocides, particularly phenoxarsines, which can be dissolved per amount of carrier.
Although aryl alkanols have proven to be advantageous cosolvents with respect to the amounts of microbiocides which may be carried into a polymer per amount of cosolvent, there has been found to be a problem with respect to shelf-life. Compounds that contain a carrier, such as a plasticizer, a microbiocidal agent, such as a phenoxarsine, and an aryl alyanol cosolvent exhibit instability due to what appears to be a UV-catalyzed oxidation of the microbiocide. Oxidation of the microbiocide, of course, reduces the effective concentration of the microbiocide; however, this is a relatively minor problem. A major problem with microbiocide oxidation is precipitation of the oxidation products; crystals of oxidation products are frequently found to occur in compositions comprising plasticizers, microbiocides and aryl alkanols.
Crystals of oxidation products are problematic in at least two important respects. Crystals in the composition are detrimental to processing of a polymer and are detrimental to the final product. In addition, crystalization of oxidation products provides nuclei for crystalization of the microbiocide itself, and more microbiocide may be lost through such crystalization than through direct oxidation of the microbiocide.
The problem of UV-catalyzed oxidation and subsequent crystalization and precipitation is found to not only occur with aryl alkanols but generally when using solvents containing an alkanol group, such as isodecyl alcohol. It is, therefore, a general object of the invention to provide compositions containing a microbiocide and a cosolvent therefore which are resistant to UV-catalyzed oxidation of the microbiocide.